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How can I place a # symbol inside of a \PackageWarning inside of a macro definition? I tried:

\PackageWarning{package}{# or \# or \string# or \hash}

but either ## or unknown (for \hash) or Illegal parameter number in definition of \reserved@a resulted.

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up vote 13 down vote accepted

Actually \string# is the way to go, however you seem to use \PackageWarning as part of a macro definition so you have to double it: \string##. The macro definition of \reserved@a might happen internally in a macro you are using. Some if-macros from the LaTeX core for example store both clauses in such temporary macros.

You could also define a macro for this character which then can be used in all \PackageWarnings and other messages independent if they are in a macro definition or not.


Then use \hashchar in the message. If you want a space behind it you need to use \space explicitly.

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\edef\hashchar{\string#} – egreg Oct 19 '11 at 12:39
@egreg: Indeed! Sometimes I think to complicated, even if the simply solution is right before my nose :-) – Martin Scharrer Oct 19 '11 at 12:49
@egreg: Works and has got the advantage to be usable inside and outside of another macro. +1 for this. – Stephen Oct 19 '11 at 12:59
As a side note, for LaTeX3, weve gone for letting \#` be that single hash character within messages. Same with a couple of standard special characters. – Bruno Le Floch Oct 19 '11 at 21:02

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